VCFD Determines Cause of the Thomas Fire

After a thorough investigation, the Ventura County Fire Department (VCFD) has determined the Thomas Fire, which occurred in December 2017, was started by power lines coming into contact during high winds. The Thomas Fire started on the evening of December 4, 2017 and burned a total of 281,893 acres; destroying 1,063 structures and resulting in one civilian and one firefighter fatality.

A high wind event caused the power lines to come into contact with each other, creating an electrical arc. The electrical arc deposited hot, burning or molten material onto the ground, in a receptive fuel bed, causing the fire. The common term for this situation is called “line slap,” and the power line in question is owned by Southern California Edison.

In total, the Thomas Fire burned for nearly 40 days, threatening the cities of Santa Paula, Ventura, Ojai and Fillmore, as well as many unincorporated communities, before moving into Santa Barbara County. It was declared 100 percent controlled on January 12, 2018. At one point, nearly 9,000 emergency personnel were working the fire. Firefighters and emergency responders came from across the western United States to help.

VCFD investigators were dispatched with initial attack resources to the wildfire and immediately began working to determine its origin and cause. An investigative team was comprised of the following agencies: CAL FIRE, Ventura County Sheriff’s Office (VCSO), Santa Barbara County Fire Department, and the U.S. Forest Service (USFS).